If you're on a tight budget, get a Mac Mini (which is essentially a Macbook in a dinky case) and provide your own screen and peripherals.
This, even if you're not on a budget. They're plenty powerful enough. My screen started going on my old g5 about 6 months after the warranty ran out. Had to replace the whole thing as it wasn't worth the repair charges. Wouldn't buy another self contained iMac again.
"Play the best song in the world, or I'll eat your soul."